This invention relates to a time division transmission system and, more particularly, to circuitry for providing an interface between time division multiplex lines and a communication switching system.
Traditionally, time division multiplex lines have been connected to a telephone switching office by means of an interface circuit which is commonly known as a D-bank. The D-bank will generally comprise time shared common circuitry and a number of channel units each of which is connected to a trunk interface circuit, referred to as a trunk circuit. The trunk circuit is interconnected to the switching network, and all control of communication over the multiplex transmission facilities is accomplished by control of the trunk circuit from the switching system controller. Such an interconnecting arrangement with multiple interface connections results in duplication of hardware, limits the access of the central processor to the transmission interface for signaling and maintenance purposes, and in many instances results in time consuming tasks by the central processor which place a significant real-time burden on the processor.